leela krishhna

abstract class Foo
{

}

What is the use of abstract key word at here,
even though i am not declare any method in this class..

Requirement:

class A
{
void m1()
{
System.out.println("Hello JAVA");
}
}

For the above class A, we need to create 5 Obects only,
If we try create 6th object it will returns the same reference of previous..
(Means we need to create only 5 Objects)

sorting on date type...the problems is typecasting in date to string again string to Date.


package com.demo; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Comparator; import java.util.Date; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Collections; public class Computer { public static int id; private String name; private int date; public Computer(int id,String name,int date){ this.id = id; this.name = name; this.date = date; } public String toString(){ return (id+""+name+""+date); } public abstract class CompDate implements Comparator<Computer> { private int mod = 1; public CompDate(boolean desc) { if (desc) mod =-1; } @Override public int compare(Computer arg0, Computer arg1) { return mod*arg0.date.compareTo(arg1.date); } } } public static void main(String arg[]){ SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy"); ArrayList <Computer> comp= new ArrayList <Computer>(); try{ comp.add(new Computer(1234,"hp",23/01/2012)); comp.add(new Computer(4567,"Compaq",03/12/2011)); comp.add(new Computer(7890,"dell",20/07/2012)); } catch(Exception e){ e.printStackTrace(); } Collections.sort(comp, Computer.CompDate(true)); System.out.println("by date asc"); for (Computer c: comp){ System.out.println(c.toString()); } } }

In the below Code, i have the File qwer.vmg, which is not reading..
It showing errors.. how can i read that file...
Please give me solution.. or way to solve it...

import java.io.*;
class FileRead
{
public static void main(String args[])
{
try{
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream("qwer.vmg");
// Get the object of DataInputStream
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
//Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console
System.out.println (strLine);
}
//Close the input stream
in.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
}

Finding no.of Objects created for a class...
I finally got this code...
Any modifications, please suggest

public class Demo { public static int count=0; //Intance block { count++; } //Constructors Demo(){ } Demo(int x){} Demo(int x,float y){ } Demo(int x,int y,int z){ } Demo(int x,int y,int z,float p){ } public static void main(String args[]) { Demo t1=new Demo(); Demo t2=new Demo(1,2.5f); Demo t3=new Demo(4); new Demo(); Demo t4=new Demo(); Demo t5=new Demo(5,6,7); Demo t6=new Demo(5,6,7,6.8f); System.out.println("The Number of Objects created for class is = "+Demo.count); } }

How to create simple User defined Immutable class...

How increase that static value every time of creating objest..

Please give the code for it...

How to find the Number of objects that are created for a particular class...

Mention any referral example code....

leela krishhna wrote:Is Servlet is Singleton class or not..

Why ,I need Reason.. Any practical proof is there...

Is Servlet is Singleton class or not..